Centerless grinding machine



Patented July 30, 19 29..

UNITED stares PATENT ;OFFHCEa-f CHARLES H. NORTON, OF PLAINVILLE, CONNECTICUT, ASSIGNOR, BY MESNE ASSIGN- MENTS, TO CINCINNATI GRINDERS INCORPORATED, .013 CINCINNATI, OHIO, A COR- oRA'r'IoN or OHIO.

CENTEBLESS GRINDING MACHINE.

. Application filed November 24, 1922, Serial No. 603,075. Renewed October 4, 1928.

maticallygrinding irregularly shaped cylindrical objects.

The usual type of centerless grinding machine comprises a rotatable grinding wheel and a fixed work support along which the work is moved axially and rotated by a regulating wheel past the face of the grinding wheel, as in Heim Reissue Patent No. 15035. \Vith such a construction it has been difficult to grind irregularly shaped articles such. as bolts which have enlarged heads thereon and cannot therefore be slid past 1 both wheels and along the worksupport.

' It is a dominant aim of this invention to provide a grinding apparatus in whlch -11- regularly shaped artlclcs having cyllndrical or round portions and shouldered or headed portions may be ground rapidly, with a highdegree of accuracy and with the achievement of the many advantages flowing from the centerless grinding apparatus disclosed in ner and without unduly complicating the construction while achieving a dependable control of the movement of the work piece into or out of the grinding zone or throat. Another object of this invention is to provide an apparatus in which the regulating .wheel and the grinding wheel are made to coact upon the work piece in a manner toinsure', even though the work piece cannot be moved completely past the adjacent surfaces of the two wheels, thoroughly practical and accurate grinding operations thereon by the grinding, wheel. Other objects will clearly described be in part obvious or in part pointed out hereinafter.

' The invention accordingly consists in the features of construction, combinations of elements, and arrangements of parts as will be exemplified in the structure to be hereinafter described and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings in which I have shown by way of illustration one of various possible embodiments of my invention, and in which like reference characters Fig. 4 is a perspective view of the work support removedv from the machine.

Referring now to the drawing, I have shown the grinding apparatus comprising a suitable. base 10 on which are rotatably mounted the two abrasive wheels 11 and 12, mounted so that their axes are preferably parallel to each other, and substantially between the adjacent operative surfaces of these wheels is sup orted, in a manner more ereinafter, a work support 25 adapted to hold the work piece in operative relation to the two wheels. The Wheel 11, which serves as the grinding wheel, may be suitably mounted for movement toward and from the work. To this end I provide a slide ltslidably mounted on the usual V and flat ways 15 and 16 on the base 10. The wheel 11 is suitably mounted on a spindle 17 suit-ably journaled in bearings on'the slide. In order that the grinding wheel may be moved toward and from the work," I provide a suitable mechanism such as that shown for example in my prior Patent No. 762,838 of June 14,1901/ As illustrated, this may comprise a half-nut 18 depending from the underside of the slide 14 and engaging a screw 19 suitably supported in the base of the machine. This screw may be rotated from'the front of the -'machine by means of a gear 20 on the screw shaft meshing with a small gear 21 such asshown in myprior patent for finely adjusting the position of the grinding wheel.

The work 24 issupported on or-held by a work rest work-holding member 25 and is rotatated while being ground'by the grind-- ing wheel 11. This rotation is effected or controlled by the other wheel 12 which is preferably mounted for both vertical and transverse movements relative to the work, so that the wheel 12 ma be located in contact with the work an above it aspossible and which, for the purose of controlling the rotation of the work, is driven in the manner herelnafter moreclearly described. 'To this end, I mount the wheel 12 in bearing housings 27 projecting from the slide 28 which is provided with the usual dovetailed slide ways fitted on similar ways 29 on the upright support 30. The slide 28 may be suitably located on the support 30 'by means of the usual nut and screw construction, as indicated in dotted line in Fig. 1, the screw 31 being operated by the hand wheel 32.

In order to-move the wheel 12 toward the work, I mount the upright member 30 on a slide 34 which has a dove-tailed connection with the upstanding member 35 on the base 10. This slide 34 is moved transversely by means of the hand wheel 36 which operates a screw 37 threaded into" the base member 35. The slide 34 carries adownwardly projecting end cap 38 which is engaged by collarsfiXed on the screw shaft to move the slide in accordance with the usual construcable mechanism, but in order to simplify the illustration I have merely indicated a belt 40 connected to drive the wheel 11 and a belt 41 to rotate the wheel 12. The wheel 11 is preferably-rotated at a rapid rate to give a suitable grinding action and the wheel 12 at a much slower rate but in the same peripheral direction as illustrated by the arrows in Fig. 1 the wheels thus presenting adjacent operative surfaces traveling in opposite direction, and the wheel 12 being preferably of abrasive material. The wheel 12 serves to regulate the speed of the work as well as to assist'in stcadying it on its support as grinding proceeds.

In accordance with certain features of my invention, I prefer to move the work axially into the grinding zone by traversing the support or work-holding member 25 with the Work 24. While Various methods of grinding may be employed, I preferably move the work into contact with the near' corners of the wheels and then grind the same as it traverses axially-until it has come into full contact with the whole peripheral preferably as far employ sucha construction that this period of relative immobility may be permitted. After the work has been ground to the desired size it is then withdrawn from contact with-the wheels and preferably to its initial starting position.

I have found'that a satisfactory Work support or work-holding member is one which has a concave partial cylindrical surface 45 and preferably one of 'the same [radius as that of a finished piece of work,

it being'noted that a new'work'support or holding member is preferably employed for each different size and shape of work that. is

to be ground. This work-holding member 25 is shown'in the drawings as a work support and is preferably so located that the center of the work is held below a line connecting the centers of the wheels 11 and 12 and the side portions of the cylindrical surface 45 are extended sufliciently so that the thrust from each wheel through the center of the work will be received by them. The wheel 12 being preferably as far above the work as possible and with the work support thus constructed, there-will be no tendency for the work to vibrate or chatter and the resultant of the various grinding forces will tend to hold the work firmly in position on its support. A distinct advantage in shaping the work support or holding member 25 to have a concave work engaging surface 45 v resides in the fact that, when the work sup port 25 is withdrawn into a position subtating action thereon.

To provide for interchangeability of work supports, I may form a dovetail portion 46 on the bottom of the member 25' and secure it on the slide 47 by a clamping member 48 which, cooperating with a portion of the slide, forms a dovetailed groove corresponding with the lower projecting portion of the work'support. The slide 47 is provided with an undercut portion which forms a slide way 49 adapted to fit a dovetailed slide member 50 mounted on theportion 35 of the base. In order to grind the cylindrical surface of a member which has an enlarged head, such as a bolt, I may provide a groove 52 in the work support which provides space for the head of the Work and serves'to prevent axial movement of the work relative ous types of mechanism, but I have illustratively shown in the drawings a preferred embodiment; this includes a cam controlled automatically operated device which will be satisfactory and has a number of peculiar advantages for this purpose. A plunger 55 fastenedat one end to the work support is mounted for reciprocation in a sleeve 56 (see Fig. 3) which is in turn supported on the.

' standard 57 (see Fig. 2) bolted to the base 10.

A pin 58 projects laterally from the plunger 1 through a slot in the casing 56. The pin or cam follower 58 is adapted to be moved by the cam 59 which is mounted on the shaft 60 supported in suitable bearings 61 and rotated by the belt driven pulley 62..

Thecam as thus shown is adapted to move the work support toward the grinding wheel 11 and work rotating wheel 12 against the action of a spring 64 which surrounds the plunger 55 and engages a head 65 thereon and the end of the sleeve 66. It will therefore be seen that this spring will tend to retract the work'support whenpermitted by the cam and cause the work to move back out of contact with the wheels at a controlled rate. This cam may be shaped and mounted. to give a desired motion'and preferably to move the work at a uniform rate until it has come into full grinding contact with the wheel, after which the work may be held stationary momentarily while the wheel grinds its way out.

In- Fig. 2 of the drawings I have shown the cam as having its periphery made up of circular portions 68 and 7 O which are concentric relative to the axis of rotation of the cam. The portion 70 provides for a short period of rest during which the work support is held longitudinally immovable after the work is withdrawn from operative relation to the wheels thus giving the operator timeto replace the finished piece of work with a new piece of work to be ground. The portion 68 provides for aperiod of rest during which the work is in full operative contact with the wheels during whichthe work and support are longitudinally 1mmovable. The two connecting or intermediate portions 67 of the cam, preferably portions of a heart shaped cam, are designed to give a uniform motion to the work support and the work supported thereby into and out of operative relation to the adjacent' operative surfaces of the two wheels.

The operation of this device will be apparent from the above disclosure. If ajpiece of work 24-, as shown in Fig. 3, is placed upon the work-support 25 at a time when the work reciprocating mechanism has brought the support 25 into the position substantially as shown in Figs. 2 and- 3. The

subsequent action of cam portions 67 moves the support 25 and the Work 24 to the left, forcing the latter first against the adjacent peripheral edges and then in between the adjacent surfaces of the two wheels and, depending upon the distance apart of the two -wheels, a heavy cut will be taken across the cylindrical face of the work piece until the latter has traversed its full extent and until the head 69 of-the work piece 24 is brought into substantial contact with the side faces of the wheels. The work then dwells under the action of cam portion 68, permitting ample time for the spring of the machine parts to be taken out and for the wheel 11 to finish its out. Then the cam portion 67 permits the spring 64 to act and to draw the work support 25 and the work piece 24:

thereon back and out of contact with the wheels. During this latter or withdrawal movement, the work, continuing to be rotated under the control ofthe work rotating wheel 12, receives a polishing finish by the grinding wheel 11, as the work thus leaves the zone of action of the two wheels. These features of construction and action are particularly adapted for grinding cylindrical articles which require a relatively highly polished or smooth surface, it being particularly noted that peculiar advantages are achieved in having the operation upon thework piece take place during the two'strokes of a single reciprocation of the work sup port and the work thereon; the grinding wheel 11, during'one stroke of movement, first accomplishes the roughing operation of grinding away the desired amount of stock and then, during the other or reverse stroke of movement, puts a finished surface on the article.- Such advantages as these will be seen to be successfully achieved with apparatus of simple but thoroughly practical construction and capable of dependable and reliable operation. It will be understood, however, that, if desired, the- Work piece may be passed through the above-described cycles of operation several times, depending upon various factors to be met with in practice, suchas, for example, the amount. of material which it is found desirable to remove at a single pass.

It will thus be seen that there has been provided in this invention an apparatus in which the several objects hereinbe fore noted, as well as many thoroughly practical advantages, are successfully achieved. It will furthermore be seen that the apparatus is well adapted to meet the conditions of vary- I ing practical use.

As many possible embodiments'may .be made of the above invention and as many changes might be made in the embodiment above set forth,- it is to be understood that all matter h'ercinbefore set forth or shown tatable grinding to' rotate and grind the work and means toin the accompanying drawing-is to be in- 'terpreted as illustrative and not in a limit-' ing sense.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is 1. In grinding apparatus, in combination, a grinding wheel, a work rotating wheel, means for driving the grinding wheel at a grinding speed, means for-driving the other wheel at a relatively low speed to control the rotation of work of round section interposed between it and the grinding wheel, said Wheels presenting adjacent operative surfaces traveling in opposite direction, a

work support movable in the direction of the grinding throat [formed by said two wheels,

and adapted to hold thereon work of round section against displacement relative to the work support as the latter is moved, means for guiding said work support in a path of movement extending in the general direction of the grindingthro'at, and power actu} ated means for moving said support'along said guiding means and thereby-move the work supported thereon into operative contact with the adjacent operative surfaces ofsaid two wheels.

2. A grinding machine comprising a rowheel, a regulating wheel opposed thereto, a movable centerless work positioning member having a concave partial cylindrlcal surface of the radlus of the.

finished work, means to rotate said wheels movethe work positioning member parallel with the work axis and present the rotating work 'to the grinding face of the wheel.

3. In grinding apparatus, in combination, a grinding wheel, a work rotating wheel opposed thereto, means for supporting work of round section between and in contact. with the adjacent operative surfaces of sald wheels, means for rotating the grinding wheel at a grinding speed to grind the work.

and for rotating said work rotating wheel slowly to rotate the work during the grind- -ing action thereon by said grinding wheel, and a positively actuated mechanism for moving the work support substantially parallel withthe axial line .ofthe work during the grinding operation, said parts )eing so constructed and arranged that the work may be ground while-moving axially.

- 4. A grinding machine comprisingv a pair of opposed abrasive wheels adapted for simultaneous grinding and rotating action. upon work of round section interposed there.- between, a movablework support adapted to'position the work between and in contact with the operative faces of said wheels, means to rotate the wheels to grind and rotate the work, and positively actuated means to traverse the work support to reciprocate the work axially while in contact with the opposed faces of said wheels.

' 5. A grinding machine comprising a rotatable grinding wheel, means including a lone gitudinally movable centerless work support adapted to rotate and hold the work in grinding contact with said wheel, means to rotate the wheel for the grinding action, and means for traversing said support to move the rotating work axially while in grinding contact with the abrading face of the grinding wheel and thereafter permit the work to be rotated and ground while remaining 1011".

gitudinally immovable in full contact with the wheel.

- 6. A grinding machine comprlsmg opposed abrasive wheels, a movable centerless support therebetween adapted to hold the work in grinding and rotative contact with the wheels, means to rotate the wheels, and operating mechanism to move the support to grind the work progressively from one end to the other, then permit it to be ground while rotating but remaining longitudinally immovable and thereafter grind the work progressively toward one end to finish the surface thereof. 7

'7. A grinding machine comprising peripherally opposed abrasive wheels having parallel axes, one for grinding and the other for rotating the work, a centerless work support having a concave face adapted to support the work between andin contact. with movable centerless support having a concave work supporting surface, and cam operated mechanism to move the work support .parallel with the axis of the work'to present the latter progressively to the grinding 'action of the wheel.

9. A grinding machine having a base, a grinding wheel rotatively mounted thereon, a centerless work support slidably mounted on said base and having a concave partial cylindrical surface of the same radius as radius of the finishedwork arranged to sup-- port the work in contactwith said wheels and out of line with their centers, andmeans surfaces of said wheels, and mechanismiorthe finished work to hold the work in grind ing contactwith the wheel, means to rotate the'wheel to grind the work, and automatically operating mechanism to reciprocate the support and the work carried thereby paral lel with the work axis, and traverse the. work progressively across the operative face of the wheel and return.

10. A centerless grinding machine comprising opposed rotatable abrasive wheels, adapted to effect simultaneous rotating and grinding action upon round work interposed therebetween,. means to rotate the same, a movable centerless work support having-a concave partial cylindrical surface of the to reciprocate said supportlongitudinally Y parallelwith the work axis to traverse the;

work progressively across the peripheral ,faces of said wheels and return. j

11. A centerless grinding machine having a base, a grinding wheel slide transversely movable thereon, a rotatable grinding wheel mounted on said slide, a support to hold the work in contact with the grinding wheel, a slide carrying said support mounted for iongitudinal movement parallel with the work axis, a second abrasive wheel operatively opposedto the grinding wheel, means to move it transversely into*contact with the work, means to rotate said Wheel at a speed to control the rotation of the work, and auto matically operated means to reciprocate said work support and slide to'traverse the'work relative to said wheels. g

12. A centerless grinding machine comprising a base, a slide transversely movable thereon, a grinding wheel rotatably mounted on said slide, a worksupporting slide movable parallel with the axis of t-hegrinding wheel, said worksupporting slide having .a concave surface fitting the finished work which is'adapted to hold the work in contact with the grinding wheel, a work rotating I wheel peripherally opposed to the grinding wheel, a transversely adjustable slide mount-' ed on said base, a'vertically adjustable slide movable thereon and carrying said work ro- -tating wheel, and, automatically operated mechanism to move the work supporting slide longitudinally and parallel with the work axis to carry the work into full grinding contact with the wheels. p

13. A'grinding machine having a base, a grinding wheel rotatively mounted thereon, a work rotating wheel opposed thereto, a work positioning member slidably mounted on said base and arranged to hold the work in operative contact with the wheels, means to rotate the wheels, the work rotating wheel slowly, thereby to regulate the work rotation and thegrinding wheel rapidly to grind the work, and automatically operating mechanismto reciprocate the positioning memberand the work carried thereby parallel with the work axis and traverse the work progressively across the faces of the wheels.

14.111 grinding apparatus, in combination, a. grinding wheel, a; work rotating 1 wheel, means for driving the grinding wheel at agrinding speed, means for driving the other wheel at a. relatively low speed to control the rotation of work of roundsection interposed between it and the grinding wheel, said wheels presenting adjacent operative surfaces'traveling in opposite directions, a work'support movable in a direction to carry the work supported thereon into operative relation to the adjacent operative giving said work support and the work su ported thereon a movement to carry t e work: into operative relation to the two wheels thereby to effect aufirst grinding operation by said grinding wheel, then to performing a third grinding operation on the work during the latter stage of movement. 1

15. In grinding apparatus, in c ombina-n' tion, a grinding wheel, a work rotating.

wheel, means for "driving the grinding wheel at agrinding speed, means for driving the other wheel at a relatively low speed to control the rotation of work-of round section interposed between it and the grindingwheel, said wheels presenting adjacent op erative surfaces traveling in opposite directions, a work support movable in a direction to carry the work supported thereon into operative relation tothe adjacent operative surfaces of said wheels, and-a cam for controlling the movement of the work support and of the work supported thereby, said cam having a portion effective to move the work into operative relation to the two wheels, an

other portion-adapted to permit the work to remain immovable while'in operative contact with both wheels, and another portion elfective to move the work out of operative relation to the two wheels, said parts beingso constructed and arranged that the grind-- ing wheel performs three substantially sue cessive grinding operations, each operation being performed while one of said cam portions is effective.

' Signed at Worcester, Massachusetts, this 16th day ofNovember, 1922..

CHARLES H. NORTON. 

